Many systems exist today that aid geographical navigation or detect geographically dispersed objects, including sonar, computer-aided navigation and radar systems. Sonar has long been used to detect waterborne or underwater objects, such as bottom topography, detect fish or other waterborne contacts, locate wreckage, etc. Due to the limitations to underwater visibility, sonar is typically the most accurate way for individuals to locate objects underwater.
Computer-aided navigation systems in use today include satellite navigation systems such as the global positioning system (GPS), Global Navigation Satellite System (GNSS), and derivations thereof. These satellite navigation systems generally enable very accurate location determination or position fixing by utilizing measurements of precise timing signals broadcast from a constellation of GPS satellites in orbit around the earth. Location can be determined, for example, on a map in terms of longitude, latitude and/or altitude, and may be determined regardless of time, weather and location.
Radar has long been employed in applications such as navigation, air traffic control, fire control, etc. For example, radar may be used to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain.
Since the development of sonar, computer-aided navigation and radar systems, display technology for these systems has also improved to enable better interpretation of their data. Paper chart recorders and other mechanical and/or manual output devices have been replaced by, for example, digital displays such as LCDs (liquid crystal displays). A display device may be configured to present a scrolling sonar chart reflecting sonar data about the location of a sonar system, a moving map reflecting navigation data about the location of a satellite-navigation receiver, or a plan position indicator (PPI) display reflecting radar data about the location of a radar system. In some instances, a combination of sonar data, navigation data and/or radar data may be provided in different respective windows on a single display device. For example, the display device may provide a combination of two separate windows, one presenting navigation data and the other presenting sonar data.
Although display technologies for sonar, computer-aided navigation and radar systems have improved to enable better interpretation of their data, it is generally desirable to continue improvement of existing technologies.